The research deals with the characterization and purification of the beta-adrenergic receptor and with the mode of coupling between the beta-adrenergic receptor and adenylate cyclase. The characterization of the beta-receptor is conducted by two independent approaches: (a) Solubilization and characterization of the oligomeric form of the receptor in non-denaturing detergents, and (b) the investigation of the beta-receptor subunit using a tritium labeled affinity lavel developed in our laboratory. The mode of coupling between the beta-receptor and adenylate cyclase is studied using a variety of techniques. We have recently demonstrated that the reversal of Gpp(NH)p activated state occurs by the "collision coupling" mechanism, similar to the mechanism responsible for the activation of the turkey erythrocyte adenylate cyclase by beta-receptors. These temperature dependencies strongly support the view that the mode of coupling of the receptor to the enzyme is of the "collision coupling" type. Currently we are also looking into the process of agonist dependent uncoupling which is the first and most important step of desensitization.